milica Articles, Embryology Leave a comment   , , ,

The process of ovulation occurs every month in the organism of the woman. It consists of the egg leaving the ovary and falling into the Fallopian tube. There are two ovaries in the female reproductive system that take turns in releasing a ready for fertilization egg.

As an infant when gonads are formed, primordial germ cells move and find their place in the gonads. Then these cells differentiate into oogonia. Typical of these cells is that they divide using mitosis multiple times and increase in number. Each cell then is surrounded by a circle of epithelium cells that are flat, called follicular cells. Read more

Embryology – the study of early human development

milica Articles, Embryology, Microbiology Leave a comment   , , , , , ,

What is Embryology?

Embryology is a study following each stage of early human development, the so called prenatal development. The name derives from the Greek word “embryo” which means unborn and “logus” which stands for science, therefore this is a science which studies the unborn.

What is a prenatal development?

Embryology analyses all of the processes that form the human being – from the forming of the reproductive cells all the way to the formation of the fetus body and organs.  Prenatal development means the developmental process of forming a fetus from a single cell. The whole process could be derived in two stages. The first one is called organogenesis and the second is the fetal period.

Organogenesis includes the first 8 weeks after conception. It studies the processes of forming the zygote and the organ primordia. The zygote is the diploid cell forming as the result of uniting the male reproductive cell – sperm and the female reproductive cell –  oocyte. Both of those cells are haploid and in their union they form a diploid zygote. This is really important in keeping the specific genome of the particular specie. For example, each human has 46 chromosomes in each of their cells. That means they are diploid or 2n.These chromosomes are homologous and therefore form 23 pairs. Each reproductive cell has 23 chromosomes formed during gametogenesis, therefore they are haploid (n).  This makes it possible when fusing the sperm and the oocyte each with 23 chromosomes to create a 46 chromosome carrying cell – the zygote.

The fetal period includes the time between 9th week of pregnancy until birth. During fetal period cells, tissues and organs keep on differentiating, while the fetus gains weight and increases in size.

It has been proven that different factors can have an influence on prenatal development. More vulnerable to such effects is the stage of organogenesis, because this is the time where each organ forms. During fetal period organs keep on developing but their basic structure is already formed. Factors could have an effect during fetal period as well, but it would not be that strong as in organogenesis.

Why is Embryology important for us?
In the past embryology had more of an observing importance, rather than today where its knowledge is used to take care of different problems during pregnancy. Most of these problems have an impact on the postnatal development as well.  Many experiments and findings in other  sciences are extremely important in Embryology. They have fundamental importance in understanding each process that leads to the forming of a fetus.  Embryology gives us a chance to create better health care strategies, therefore there would be better outcomes in reproduction.  Having more and more knowledge makes it possible to have better techniques for prenatal diagnosis, treatments, solving the problems of infertility, preventing birth defects. A great percent of the abortions and child’s death is caused by birth defects. For example there is a type of numerical abnormality in chromosomes, where the fetus has 47 instead of 46 chromosomes. In such cases a particular pair of chromosomes has not two but three chromosomes. This is called trisomy. Trisomy 13is an abnormality where the fetus has three chromosomes of number 13. More than 90% of the children die before they were even given birth.  
Normal chromosome number and structure


Trichomonas vaginalis

milica Articles, Parasitology 1 , ,


     Trichomonas vaginalis is a flagellated protozoan, which means it contains only of one cell, which has cytoplasma and nucleus, seperated from the outside world by a cell membrane.

The parasite has 4 flagella on the front end of the cell and one going vertically to the body. It differentiates the so called undulating membrane. The nucleus is situated in the front of the cell. On the opposite side of the undulating membrane, in the front end of the cell, there is a cytostome. A conspicuous barb-like axostyle projects opposite the four flagella, coming out from the back end of the cell. Its lenght is 7 to 30 micrometers. It has no cyst form but it is possible to live up to 24 hours in urine, semen or even water.

It does not have mitochondria and therefore the necessary enzymes and cytochromes in order to conduct oxidative phosphorylation. Therefore the needed proteins are transmitted throughout the cell membrane. Some of the needed substances are gothered by phagocytosis. The needed energy is acquired by anaerobic breaking of glucose to glycerol and succinate in the process of glycolisis.

This parasite is found in the vagina of  women and urethra of both men and women. It is one of the most common parasites on earth. The acidity in the vagina ( pH 5,9 to 6,5) makes it extremely enviramental-friendly for the parasite.

The way this parasite is transmitting is by sexual interaction. With men there is usually no signs of an infection. However, women experience in most cases symptoms such as a fluid, different in colour – from yellowish to greenish, called vaginal fluid. This is due to the infection of the vaginal wall, called colpitis, caused by the parasite.

T. vaginalis is also known to cause different complications such as low birth weight, preterm delivery, predisposing to HIV infection, cervical cancer. It is also found in the urinary tract, fallopian tubes and pelvis, as it can cause pneumonia, bronchitis and oral lesions.

Treatment is considered to be extremely hard but not impossible. Usually antibiotics are prescribed – metronidazole or tinidazole. Since it is really easy to be infected, again in most cases there is treatment provided for both sexual partners. Even though men experience most of the times no symptoms they are still transmitting the parasite to their sexual partners. Symptoms with men could be those of urethritis(purulent or clear discharge).

Using condoms in order to prevent transmitting this parasite reduces the chances of  doing so, but NOT completely.